#include <iostream>
#include <string>
#include <cstdlib>
#include <unistd.h>
#include <sys/types.h>
#include <sys/wait.h>

// Father -> write
// Child -> read

int main()
{
    // 1.创建管道
    int fds[2] = {0};
    int n = pipe(fds);
    if (n != 0)
    {
        std::cerr << "pipe error" << std::endl;
        return 1;
    }

    // 2.创建子进程
    pid_t id = fork();
    if (id < 0)
    {
        std::cerr << "fork error" << std::endl;
        return 2;
    }
    else if (id == 0)
    {
        // 子进程
        // 关闭不需要的fd 关闭write
        close(fds[1]);

        char buffer[1024];
        while (true)
        {
            ssize_t n = ::read(fds[0], buffer, 1024);

            if (n > 0)
            {
                buffer[n] = 0;
                std::cout << "father -> child, message: " << buffer << std::endl;
            }
            sleep(1);

        }
        close(fds[0]);
        exit(0);
    }
    else
    {
        // 父进程
        // 关闭不需要的fd 关闭read
        close(fds[0]);

        while (true)
        {
            std::string message = "I am father";

            // fds[1]
            ::write(fds[1], message.c_str(), message.size());
            //sleep(1);
        }
        
        int status = 0;
        pid_t rid = waitpid(id, &status, 0);

        std::cout << "father wait child success: " << rid <<"exit code" << 
        ((status << 8)&0xFF) << " , exit sig: "<< (status & 0x7F) << std::endl;
    }

    return 0;
}
